1 /* 2 * linux/fs/ext4/balloc.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993 10 * Big-endian to little-endian byte-swapping/bitmaps by 11 * David S. Miller (davem@caip.rutgers.edu), 1995 12 */ 13 14 #include <linux/time.h> 15 #include <linux/capability.h> 16 #include <linux/fs.h> 17 #include <linux/jbd2.h> 18 #include <linux/quotaops.h> 19 #include <linux/buffer_head.h> 20 #include "ext4.h" 21 #include "ext4_jbd2.h" 22 #include "mballoc.h" 23 24 #include <trace/events/ext4.h> 25 26 static unsigned ext4_num_base_meta_clusters(struct super_block *sb, 27 ext4_group_t block_group); 28 /* 29 * balloc.c contains the blocks allocation and deallocation routines 30 */ 31 32 /* 33 * Calculate block group number for a given block number 34 */ 35 ext4_group_t ext4_get_group_number(struct super_block *sb, 36 ext4_fsblk_t block) 37 { 38 ext4_group_t group; 39 40 if (test_opt2(sb, STD_GROUP_SIZE)) 41 group = (block - 42 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >> 43 (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3); 44 else 45 ext4_get_group_no_and_offset(sb, block, &group, NULL); 46 return group; 47 } 48 49 /* 50 * Calculate the block group number and offset into the block/cluster 51 * allocation bitmap, given a block number 52 */ 53 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr, 54 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp) 55 { 56 struct ext4_super_block *es = EXT4_SB(sb)->s_es; 57 ext4_grpblk_t offset; 58 59 blocknr = blocknr - le32_to_cpu(es->s_first_data_block); 60 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >> 61 EXT4_SB(sb)->s_cluster_bits; 62 if (offsetp) 63 *offsetp = offset; 64 if (blockgrpp) 65 *blockgrpp = blocknr; 66 67 } 68 69 /* 70 * Check whether the 'block' lives within the 'block_group'. Returns 1 if so 71 * and 0 otherwise. 72 */ 73 static inline int ext4_block_in_group(struct super_block *sb, 74 ext4_fsblk_t block, 75 ext4_group_t block_group) 76 { 77 ext4_group_t actual_group; 78 79 actual_group = ext4_get_group_number(sb, block); 80 return (actual_group == block_group) ? 1 : 0; 81 } 82 83 /* Return the number of clusters used for file system metadata; this 84 * represents the overhead needed by the file system. 85 */ 86 unsigned ext4_num_overhead_clusters(struct super_block *sb, 87 ext4_group_t block_group, 88 struct ext4_group_desc *gdp) 89 { 90 unsigned num_clusters; 91 int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c; 92 ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group); 93 ext4_fsblk_t itbl_blk; 94 struct ext4_sb_info *sbi = EXT4_SB(sb); 95 96 /* This is the number of clusters used by the superblock, 97 * block group descriptors, and reserved block group 98 * descriptor blocks */ 99 num_clusters = ext4_num_base_meta_clusters(sb, block_group); 100 101 /* 102 * For the allocation bitmaps and inode table, we first need 103 * to check to see if the block is in the block group. If it 104 * is, then check to see if the cluster is already accounted 105 * for in the clusters used for the base metadata cluster, or 106 * if we can increment the base metadata cluster to include 107 * that block. Otherwise, we will have to track the cluster 108 * used for the allocation bitmap or inode table explicitly. 109 * Normally all of these blocks are contiguous, so the special 110 * case handling shouldn't be necessary except for *very* 111 * unusual file system layouts. 112 */ 113 if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) { 114 block_cluster = EXT4_B2C(sbi, 115 ext4_block_bitmap(sb, gdp) - start); 116 if (block_cluster < num_clusters) 117 block_cluster = -1; 118 else if (block_cluster == num_clusters) { 119 num_clusters++; 120 block_cluster = -1; 121 } 122 } 123 124 if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) { 125 inode_cluster = EXT4_B2C(sbi, 126 ext4_inode_bitmap(sb, gdp) - start); 127 if (inode_cluster < num_clusters) 128 inode_cluster = -1; 129 else if (inode_cluster == num_clusters) { 130 num_clusters++; 131 inode_cluster = -1; 132 } 133 } 134 135 itbl_blk = ext4_inode_table(sb, gdp); 136 for (i = 0; i < sbi->s_itb_per_group; i++) { 137 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) { 138 c = EXT4_B2C(sbi, itbl_blk + i - start); 139 if ((c < num_clusters) || (c == inode_cluster) || 140 (c == block_cluster) || (c == itbl_cluster)) 141 continue; 142 if (c == num_clusters) { 143 num_clusters++; 144 continue; 145 } 146 num_clusters++; 147 itbl_cluster = c; 148 } 149 } 150 151 if (block_cluster != -1) 152 num_clusters++; 153 if (inode_cluster != -1) 154 num_clusters++; 155 156 return num_clusters; 157 } 158 159 static unsigned int num_clusters_in_group(struct super_block *sb, 160 ext4_group_t block_group) 161 { 162 unsigned int blocks; 163 164 if (block_group == ext4_get_groups_count(sb) - 1) { 165 /* 166 * Even though mke2fs always initializes the first and 167 * last group, just in case some other tool was used, 168 * we need to make sure we calculate the right free 169 * blocks. 170 */ 171 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) - 172 ext4_group_first_block_no(sb, block_group); 173 } else 174 blocks = EXT4_BLOCKS_PER_GROUP(sb); 175 return EXT4_NUM_B2C(EXT4_SB(sb), blocks); 176 } 177 178 /* Initializes an uninitialized block bitmap */ 179 void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, 180 ext4_group_t block_group, 181 struct ext4_group_desc *gdp) 182 { 183 unsigned int bit, bit_max; 184 struct ext4_sb_info *sbi = EXT4_SB(sb); 185 ext4_fsblk_t start, tmp; 186 int flex_bg = 0; 187 struct ext4_group_info *grp; 188 189 J_ASSERT_BH(bh, buffer_locked(bh)); 190 191 /* If checksum is bad mark all blocks used to prevent allocation 192 * essentially implementing a per-group read-only flag. */ 193 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) { 194 ext4_error(sb, "Checksum bad for group %u", block_group); 195 grp = ext4_get_group_info(sb, block_group); 196 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state); 197 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state); 198 return; 199 } 200 memset(bh->b_data, 0, sb->s_blocksize); 201 202 bit_max = ext4_num_base_meta_clusters(sb, block_group); 203 for (bit = 0; bit < bit_max; bit++) 204 ext4_set_bit(bit, bh->b_data); 205 206 start = ext4_group_first_block_no(sb, block_group); 207 208 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) 209 flex_bg = 1; 210 211 /* Set bits for block and inode bitmaps, and inode table */ 212 tmp = ext4_block_bitmap(sb, gdp); 213 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 214 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 215 216 tmp = ext4_inode_bitmap(sb, gdp); 217 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 218 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 219 220 tmp = ext4_inode_table(sb, gdp); 221 for (; tmp < ext4_inode_table(sb, gdp) + 222 sbi->s_itb_per_group; tmp++) { 223 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 224 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 225 } 226 227 /* 228 * Also if the number of blocks within the group is less than 229 * the blocksize * 8 ( which is the size of bitmap ), set rest 230 * of the block bitmap to 1 231 */ 232 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group), 233 sb->s_blocksize * 8, bh->b_data); 234 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh); 235 ext4_group_desc_csum_set(sb, block_group, gdp); 236 } 237 238 /* Return the number of free blocks in a block group. It is used when 239 * the block bitmap is uninitialized, so we can't just count the bits 240 * in the bitmap. */ 241 unsigned ext4_free_clusters_after_init(struct super_block *sb, 242 ext4_group_t block_group, 243 struct ext4_group_desc *gdp) 244 { 245 return num_clusters_in_group(sb, block_group) - 246 ext4_num_overhead_clusters(sb, block_group, gdp); 247 } 248 249 /* 250 * The free blocks are managed by bitmaps. A file system contains several 251 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap 252 * block for inodes, N blocks for the inode table and data blocks. 253 * 254 * The file system contains group descriptors which are located after the 255 * super block. Each descriptor contains the number of the bitmap block and 256 * the free blocks count in the block. The descriptors are loaded in memory 257 * when a file system is mounted (see ext4_fill_super). 258 */ 259 260 /** 261 * ext4_get_group_desc() -- load group descriptor from disk 262 * @sb: super block 263 * @block_group: given block group 264 * @bh: pointer to the buffer head to store the block 265 * group descriptor 266 */ 267 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, 268 ext4_group_t block_group, 269 struct buffer_head **bh) 270 { 271 unsigned int group_desc; 272 unsigned int offset; 273 ext4_group_t ngroups = ext4_get_groups_count(sb); 274 struct ext4_group_desc *desc; 275 struct ext4_sb_info *sbi = EXT4_SB(sb); 276 277 if (block_group >= ngroups) { 278 ext4_error(sb, "block_group >= groups_count - block_group = %u," 279 " groups_count = %u", block_group, ngroups); 280 281 return NULL; 282 } 283 284 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb); 285 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1); 286 if (!sbi->s_group_desc[group_desc]) { 287 ext4_error(sb, "Group descriptor not loaded - " 288 "block_group = %u, group_desc = %u, desc = %u", 289 block_group, group_desc, offset); 290 return NULL; 291 } 292 293 desc = (struct ext4_group_desc *)( 294 (__u8 *)sbi->s_group_desc[group_desc]->b_data + 295 offset * EXT4_DESC_SIZE(sb)); 296 if (bh) 297 *bh = sbi->s_group_desc[group_desc]; 298 return desc; 299 } 300 301 /* 302 * Return the block number which was discovered to be invalid, or 0 if 303 * the block bitmap is valid. 304 */ 305 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, 306 struct ext4_group_desc *desc, 307 ext4_group_t block_group, 308 struct buffer_head *bh) 309 { 310 ext4_grpblk_t offset; 311 ext4_grpblk_t next_zero_bit; 312 ext4_fsblk_t blk; 313 ext4_fsblk_t group_first_block; 314 315 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { 316 /* with FLEX_BG, the inode/block bitmaps and itable 317 * blocks may not be in the group at all 318 * so the bitmap validation will be skipped for those groups 319 * or it has to also read the block group where the bitmaps 320 * are located to verify they are set. 321 */ 322 return 0; 323 } 324 group_first_block = ext4_group_first_block_no(sb, block_group); 325 326 /* check whether block bitmap block number is set */ 327 blk = ext4_block_bitmap(sb, desc); 328 offset = blk - group_first_block; 329 if (!ext4_test_bit(offset, bh->b_data)) 330 /* bad block bitmap */ 331 return blk; 332 333 /* check whether the inode bitmap block number is set */ 334 blk = ext4_inode_bitmap(sb, desc); 335 offset = blk - group_first_block; 336 if (!ext4_test_bit(offset, bh->b_data)) 337 /* bad block bitmap */ 338 return blk; 339 340 /* check whether the inode table block number is set */ 341 blk = ext4_inode_table(sb, desc); 342 offset = blk - group_first_block; 343 next_zero_bit = ext4_find_next_zero_bit(bh->b_data, 344 offset + EXT4_SB(sb)->s_itb_per_group, 345 offset); 346 if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group) 347 /* bad bitmap for inode tables */ 348 return blk; 349 return 0; 350 } 351 352 void ext4_validate_block_bitmap(struct super_block *sb, 353 struct ext4_group_desc *desc, 354 ext4_group_t block_group, 355 struct buffer_head *bh) 356 { 357 ext4_fsblk_t blk; 358 struct ext4_group_info *grp = ext4_get_group_info(sb, block_group); 359 360 if (buffer_verified(bh)) 361 return; 362 363 ext4_lock_group(sb, block_group); 364 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh); 365 if (unlikely(blk != 0)) { 366 ext4_unlock_group(sb, block_group); 367 ext4_error(sb, "bg %u: block %llu: invalid block bitmap", 368 block_group, blk); 369 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state); 370 return; 371 } 372 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group, 373 desc, bh))) { 374 ext4_unlock_group(sb, block_group); 375 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group); 376 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state); 377 return; 378 } 379 set_buffer_verified(bh); 380 ext4_unlock_group(sb, block_group); 381 } 382 383 /** 384 * ext4_read_block_bitmap_nowait() 385 * @sb: super block 386 * @block_group: given block group 387 * 388 * Read the bitmap for a given block_group,and validate the 389 * bits for block/inode/inode tables are set in the bitmaps 390 * 391 * Return buffer_head on success or NULL in case of failure. 392 */ 393 struct buffer_head * 394 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group) 395 { 396 struct ext4_group_desc *desc; 397 struct buffer_head *bh; 398 ext4_fsblk_t bitmap_blk; 399 400 desc = ext4_get_group_desc(sb, block_group, NULL); 401 if (!desc) 402 return NULL; 403 bitmap_blk = ext4_block_bitmap(sb, desc); 404 bh = sb_getblk(sb, bitmap_blk); 405 if (unlikely(!bh)) { 406 ext4_error(sb, "Cannot get buffer for block bitmap - " 407 "block_group = %u, block_bitmap = %llu", 408 block_group, bitmap_blk); 409 return NULL; 410 } 411 412 if (bitmap_uptodate(bh)) 413 goto verify; 414 415 lock_buffer(bh); 416 if (bitmap_uptodate(bh)) { 417 unlock_buffer(bh); 418 goto verify; 419 } 420 ext4_lock_group(sb, block_group); 421 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { 422 ext4_init_block_bitmap(sb, bh, block_group, desc); 423 set_bitmap_uptodate(bh); 424 set_buffer_uptodate(bh); 425 ext4_unlock_group(sb, block_group); 426 unlock_buffer(bh); 427 return bh; 428 } 429 ext4_unlock_group(sb, block_group); 430 if (buffer_uptodate(bh)) { 431 /* 432 * if not uninit if bh is uptodate, 433 * bitmap is also uptodate 434 */ 435 set_bitmap_uptodate(bh); 436 unlock_buffer(bh); 437 goto verify; 438 } 439 /* 440 * submit the buffer_head for reading 441 */ 442 set_buffer_new(bh); 443 trace_ext4_read_block_bitmap_load(sb, block_group); 444 bh->b_end_io = ext4_end_bitmap_read; 445 get_bh(bh); 446 submit_bh(READ | REQ_META | REQ_PRIO, bh); 447 return bh; 448 verify: 449 ext4_validate_block_bitmap(sb, desc, block_group, bh); 450 if (buffer_verified(bh)) 451 return bh; 452 put_bh(bh); 453 return NULL; 454 } 455 456 /* Returns 0 on success, 1 on error */ 457 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group, 458 struct buffer_head *bh) 459 { 460 struct ext4_group_desc *desc; 461 462 if (!buffer_new(bh)) 463 return 0; 464 desc = ext4_get_group_desc(sb, block_group, NULL); 465 if (!desc) 466 return 1; 467 wait_on_buffer(bh); 468 if (!buffer_uptodate(bh)) { 469 ext4_error(sb, "Cannot read block bitmap - " 470 "block_group = %u, block_bitmap = %llu", 471 block_group, (unsigned long long) bh->b_blocknr); 472 return 1; 473 } 474 clear_buffer_new(bh); 475 /* Panic or remount fs read-only if block bitmap is invalid */ 476 ext4_validate_block_bitmap(sb, desc, block_group, bh); 477 /* ...but check for error just in case errors=continue. */ 478 return !buffer_verified(bh); 479 } 480 481 struct buffer_head * 482 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group) 483 { 484 struct buffer_head *bh; 485 486 bh = ext4_read_block_bitmap_nowait(sb, block_group); 487 if (!bh) 488 return NULL; 489 if (ext4_wait_block_bitmap(sb, block_group, bh)) { 490 put_bh(bh); 491 return NULL; 492 } 493 return bh; 494 } 495 496 /** 497 * ext4_has_free_clusters() 498 * @sbi: in-core super block structure. 499 * @nclusters: number of needed blocks 500 * @flags: flags from ext4_mb_new_blocks() 501 * 502 * Check if filesystem has nclusters free & available for allocation. 503 * On success return 1, return 0 on failure. 504 */ 505 static int ext4_has_free_clusters(struct ext4_sb_info *sbi, 506 s64 nclusters, unsigned int flags) 507 { 508 s64 free_clusters, dirty_clusters, rsv, resv_clusters; 509 struct percpu_counter *fcc = &sbi->s_freeclusters_counter; 510 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter; 511 512 free_clusters = percpu_counter_read_positive(fcc); 513 dirty_clusters = percpu_counter_read_positive(dcc); 514 resv_clusters = atomic64_read(&sbi->s_resv_clusters); 515 516 /* 517 * r_blocks_count should always be multiple of the cluster ratio so 518 * we are safe to do a plane bit shift only. 519 */ 520 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) + 521 resv_clusters; 522 523 if (free_clusters - (nclusters + rsv + dirty_clusters) < 524 EXT4_FREECLUSTERS_WATERMARK) { 525 free_clusters = percpu_counter_sum_positive(fcc); 526 dirty_clusters = percpu_counter_sum_positive(dcc); 527 } 528 /* Check whether we have space after accounting for current 529 * dirty clusters & root reserved clusters. 530 */ 531 if (free_clusters >= (rsv + nclusters + dirty_clusters)) 532 return 1; 533 534 /* Hm, nope. Are (enough) root reserved clusters available? */ 535 if (uid_eq(sbi->s_resuid, current_fsuid()) || 536 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) || 537 capable(CAP_SYS_RESOURCE) || 538 (flags & EXT4_MB_USE_ROOT_BLOCKS)) { 539 540 if (free_clusters >= (nclusters + dirty_clusters + 541 resv_clusters)) 542 return 1; 543 } 544 /* No free blocks. Let's see if we can dip into reserved pool */ 545 if (flags & EXT4_MB_USE_RESERVED) { 546 if (free_clusters >= (nclusters + dirty_clusters)) 547 return 1; 548 } 549 550 return 0; 551 } 552 553 int ext4_claim_free_clusters(struct ext4_sb_info *sbi, 554 s64 nclusters, unsigned int flags) 555 { 556 if (ext4_has_free_clusters(sbi, nclusters, flags)) { 557 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters); 558 return 0; 559 } else 560 return -ENOSPC; 561 } 562 563 /** 564 * ext4_should_retry_alloc() 565 * @sb: super block 566 * @retries number of attemps has been made 567 * 568 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if 569 * it is profitable to retry the operation, this function will wait 570 * for the current or committing transaction to complete, and then 571 * return TRUE. 572 * 573 * if the total number of retries exceed three times, return FALSE. 574 */ 575 int ext4_should_retry_alloc(struct super_block *sb, int *retries) 576 { 577 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) || 578 (*retries)++ > 3 || 579 !EXT4_SB(sb)->s_journal) 580 return 0; 581 582 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); 583 584 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal); 585 } 586 587 /* 588 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks 589 * 590 * @handle: handle to this transaction 591 * @inode: file inode 592 * @goal: given target block(filesystem wide) 593 * @count: pointer to total number of clusters needed 594 * @errp: error code 595 * 596 * Return 1st allocated block number on success, *count stores total account 597 * error stores in errp pointer 598 */ 599 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, 600 ext4_fsblk_t goal, unsigned int flags, 601 unsigned long *count, int *errp) 602 { 603 struct ext4_allocation_request ar; 604 ext4_fsblk_t ret; 605 606 memset(&ar, 0, sizeof(ar)); 607 /* Fill with neighbour allocated blocks */ 608 ar.inode = inode; 609 ar.goal = goal; 610 ar.len = count ? *count : 1; 611 ar.flags = flags; 612 613 ret = ext4_mb_new_blocks(handle, &ar, errp); 614 if (count) 615 *count = ar.len; 616 /* 617 * Account for the allocated meta blocks. We will never 618 * fail EDQUOT for metdata, but we do account for it. 619 */ 620 if (!(*errp) && 621 ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) { 622 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 623 EXT4_I(inode)->i_allocated_meta_blocks += ar.len; 624 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 625 dquot_alloc_block_nofail(inode, 626 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len)); 627 } 628 return ret; 629 } 630 631 /** 632 * ext4_count_free_clusters() -- count filesystem free clusters 633 * @sb: superblock 634 * 635 * Adds up the number of free clusters from each block group. 636 */ 637 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb) 638 { 639 ext4_fsblk_t desc_count; 640 struct ext4_group_desc *gdp; 641 ext4_group_t i; 642 ext4_group_t ngroups = ext4_get_groups_count(sb); 643 #ifdef EXT4FS_DEBUG 644 struct ext4_super_block *es; 645 ext4_fsblk_t bitmap_count; 646 unsigned int x; 647 struct buffer_head *bitmap_bh = NULL; 648 649 es = EXT4_SB(sb)->s_es; 650 desc_count = 0; 651 bitmap_count = 0; 652 gdp = NULL; 653 654 for (i = 0; i < ngroups; i++) { 655 gdp = ext4_get_group_desc(sb, i, NULL); 656 if (!gdp) 657 continue; 658 desc_count += ext4_free_group_clusters(sb, gdp); 659 brelse(bitmap_bh); 660 bitmap_bh = ext4_read_block_bitmap(sb, i); 661 if (bitmap_bh == NULL) 662 continue; 663 664 x = ext4_count_free(bitmap_bh->b_data, 665 EXT4_BLOCKS_PER_GROUP(sb) / 8); 666 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n", 667 i, ext4_free_group_clusters(sb, gdp), x); 668 bitmap_count += x; 669 } 670 brelse(bitmap_bh); 671 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu" 672 ", computed = %llu, %llu\n", 673 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)), 674 desc_count, bitmap_count); 675 return bitmap_count; 676 #else 677 desc_count = 0; 678 for (i = 0; i < ngroups; i++) { 679 gdp = ext4_get_group_desc(sb, i, NULL); 680 if (!gdp) 681 continue; 682 desc_count += ext4_free_group_clusters(sb, gdp); 683 } 684 685 return desc_count; 686 #endif 687 } 688 689 static inline int test_root(ext4_group_t a, int b) 690 { 691 while (1) { 692 if (a < b) 693 return 0; 694 if (a == b) 695 return 1; 696 if ((a % b) != 0) 697 return 0; 698 a = a / b; 699 } 700 } 701 702 static int ext4_group_sparse(ext4_group_t group) 703 { 704 if (group <= 1) 705 return 1; 706 if (!(group & 1)) 707 return 0; 708 return (test_root(group, 7) || test_root(group, 5) || 709 test_root(group, 3)); 710 } 711 712 /** 713 * ext4_bg_has_super - number of blocks used by the superblock in group 714 * @sb: superblock for filesystem 715 * @group: group number to check 716 * 717 * Return the number of blocks used by the superblock (primary or backup) 718 * in this group. Currently this will be only 0 or 1. 719 */ 720 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group) 721 { 722 if (EXT4_HAS_RO_COMPAT_FEATURE(sb, 723 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) && 724 !ext4_group_sparse(group)) 725 return 0; 726 return 1; 727 } 728 729 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, 730 ext4_group_t group) 731 { 732 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 733 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb); 734 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1; 735 736 if (group == first || group == first + 1 || group == last) 737 return 1; 738 return 0; 739 } 740 741 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, 742 ext4_group_t group) 743 { 744 if (!ext4_bg_has_super(sb, group)) 745 return 0; 746 747 if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG)) 748 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 749 else 750 return EXT4_SB(sb)->s_gdb_count; 751 } 752 753 /** 754 * ext4_bg_num_gdb - number of blocks used by the group table in group 755 * @sb: superblock for filesystem 756 * @group: group number to check 757 * 758 * Return the number of blocks used by the group descriptor table 759 * (primary or backup) in this group. In the future there may be a 760 * different number of descriptor blocks in each group. 761 */ 762 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) 763 { 764 unsigned long first_meta_bg = 765 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 766 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 767 768 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) || 769 metagroup < first_meta_bg) 770 return ext4_bg_num_gdb_nometa(sb, group); 771 772 return ext4_bg_num_gdb_meta(sb,group); 773 774 } 775 776 /* 777 * This function returns the number of file system metadata clusters at 778 * the beginning of a block group, including the reserved gdt blocks. 779 */ 780 static unsigned ext4_num_base_meta_clusters(struct super_block *sb, 781 ext4_group_t block_group) 782 { 783 struct ext4_sb_info *sbi = EXT4_SB(sb); 784 unsigned num; 785 786 /* Check for superblock and gdt backups in this group */ 787 num = ext4_bg_has_super(sb, block_group); 788 789 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) || 790 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * 791 sbi->s_desc_per_block) { 792 if (num) { 793 num += ext4_bg_num_gdb(sb, block_group); 794 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); 795 } 796 } else { /* For META_BG_BLOCK_GROUPS */ 797 num += ext4_bg_num_gdb(sb, block_group); 798 } 799 return EXT4_NUM_B2C(sbi, num); 800 } 801 /** 802 * ext4_inode_to_goal_block - return a hint for block allocation 803 * @inode: inode for block allocation 804 * 805 * Return the ideal location to start allocating blocks for a 806 * newly created inode. 807 */ 808 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode) 809 { 810 struct ext4_inode_info *ei = EXT4_I(inode); 811 ext4_group_t block_group; 812 ext4_grpblk_t colour; 813 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); 814 ext4_fsblk_t bg_start; 815 ext4_fsblk_t last_block; 816 817 block_group = ei->i_block_group; 818 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { 819 /* 820 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME 821 * block groups per flexgroup, reserve the first block 822 * group for directories and special files. Regular 823 * files will start at the second block group. This 824 * tends to speed up directory access and improves 825 * fsck times. 826 */ 827 block_group &= ~(flex_size-1); 828 if (S_ISREG(inode->i_mode)) 829 block_group++; 830 } 831 bg_start = ext4_group_first_block_no(inode->i_sb, block_group); 832 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; 833 834 /* 835 * If we are doing delayed allocation, we don't need take 836 * colour into account. 837 */ 838 if (test_opt(inode->i_sb, DELALLOC)) 839 return bg_start; 840 841 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) 842 colour = (current->pid % 16) * 843 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); 844 else 845 colour = (current->pid % 16) * ((last_block - bg_start) / 16); 846 return bg_start + colour; 847 } 848 849